1. Field of the Invention
This invention relates to multi-layer articles made of layers of polyester resins and other kinds of materials in which the inter-layer bond strength is improved. More particularly, the invention relates to multi-layer laminate articles which comprise at least two layers including a polyester resin layer and a layer of an epoxy group-containing olefin polymer or an olefin polymer composition comprising the epoxy group-containing olefin polymer. The multi-layer articles may consist of three or more layers including a polyester resin layer and a layer of the other kind of material between which the layer of the epoxy group-containing olefin polymer is interposed. These articles have low permeability to gases such as oxygen, carbon dioxide and flavors and can be favorably used as packaging materials such as food wrap films and food packaging containers.
2. Description of the Prior Art
Since polyester resins have good characteristics such as high transparency, good heat resistance and low gas permeability, they are laminated with other kinds of materials such as polyolefins and are widely used as packaging materials for foods. However, a bond between a polyester resin and other kind of material is poor, so that the resultant laminate is very readily delaminated.
In order to improve the interlaminar bond strength of the laminates, there have been used several resins including ethylene-vinyl acetate copolymers, inonomer resins, or resins obtained by modifying polyolefins with maleic anhydride (see, for example, Japanese Laid-open Patent Applications Nos. 51-92880, 52-32080, 54-82, 54-87753 and 54-160481). Although these resins have good compatibility with polyolefin resins and polyamide resins and can be bonded therewith with high interlaminar bond strength, their adhesion to polyester resins is low.